The present embodiments relate to a selection unit for a magnetic resonance imaging (MRI) system. The selection unit connects a first number of electrical terminals to a second number of communication entities.
For substantial magnetic resonance recordings, e.g. when large or voluminous examination objects are to be depicted, it is rarely possible to complete the imaging in a single step. This may be attributable to a limited volume that can be penetrated by a homogenous magnetic field when using the magnetic resonance system.
Consequently, the magnetic resonance recording is effected in a plurality of steps. In such a case, a multiplicity of local antenna elements are usually used for a magnetic resonance signal and are already arranged before starting the first magnetic resonance recording of the examination object that is to be depicted, such that a complete image can be produced in a plurality of steps without any unnecessary delay to the imaging. However, during the image capture, only those antenna elements that are arranged within the limited volume are involved in the imaging for the respective step of the magnetic resonance recording, and a mobile support element for the examination object is moved in a plurality of steps, or passed through so-called stages, in the limited volume for imaging.
A magnetic resonance imaging system normally only has a limited number of receive points or receive channels (the number may be influenced by the limited volume of the respective imaging system) that may be connected to the local antenna elements and in which signals that are received from the antenna elements undergo further processing and are prepared for a reconstruction of image data. Therefore, the number of local antenna elements often exceeds the number of receive points.
In order to allow rapid connection of the local antenna elements to the receive points of the magnetic resonance imaging system, a selection unit that allows a change in the assignment of local antenna elements to receive points of the imaging system may be used.
The selection unit is usually arranged on a stationary part of the magnetic resonance imaging system, such that a multiplicity of connection cables need to be routed, via a flexible cable duct, from the local antenna elements to the selection unit.
This frequently has an adverse effect on the signal that is transmitted to the imaging system from the local antenna elements, such that a connection of sufficient quality, i.e., a connection in which the image quality is not significantly affected, may only be established by applying particular care in a method that is very difficult to perform.
This problem is not, however, restricted to the local antenna elements as electrical terminals.